To assess the effect of prophylactic GSK1278863 versus placebo on CSF markers (S100beta and GFAP) of central nervous system (CNS) injury. Samples of approximately 5mL of CSF will be obtained directly from the lumbar drain

Number of subjects with adverse event (AEs). [ Time Frame: Up to 45 days ] [ Designated as safety issue: No ]

AEs will be collected from the start of Study Treatment and until the follow-up contact

Electrocardiogram (ECG) measurement as a measure of safety and tolerability. [ Time Frame: Up to 45 days ] [ Designated as safety issue: No ]

Single 12-lead ECGs will be obtained at each time point during the study using an ECG machine that automatically calculates the heart rate and measures PR, QRS, QT, and QT interval corrected for heart rate intervals.

Vital sign measurement as a measure of safety and tolerability [ Time Frame: Up to 45 days ] [ Designated as safety issue: No ]

Vital sign measurements will include systolic and diastolic blood pressure and pulse rate.

Clinical observation by nurses/physician as a measure of safety and tolerability [ Time Frame: Up to 45 days ] [ Designated as safety issue: No ]

Laboratory parameter assessment as a measure of safety and tolerability [ Time Frame: Up to 45 days ] [ Designated as safety issue: No ]

This study will test the hypothesis that GSK1278863 will reduce neurologic, renal, and/or cardiac ischemia in patients undergoing elective descending thoracic aorta/thoracoabdominal aortic aneurysm (DTA/TAAA) repair, a population known to be at high risk for ischemic events from their underlying pathology and the surgical complexity required to address their disease. Approximately 160 subjects will be stratified according to intervention type (surgical or endovascular repair, with the latter limited to 50% of the total study population) and randomized in a 1:1 fashion to treatment with GSK1278863 (300 milligrams [loading dose] followed by 100 milligrams [mg]/day x 4 days) or placebo starting prior to planned repair, through postoperative day 3. The duration of participation in this study is expected to be approximately 4 to 8 weeks from screening to follow-up.

Adults >= 18 years of age who require the following types of descending thoracic aorta or thoracoabdominal aorta repair for atherosclerotic aneurysm or chronic dissection (de novo Type B or residual Type B [following Type A repair]) via open surgery or endovascular stenting (TEVAR) as per their treating surgeon

Extent IV TAAA only with a prior TEVAR or if it is a redo procedure (in this setting a "redo" is a prior abdominal aortic aneurysm (AAA) open or endovascular aortic repair (EVAR), with either proximal suture line disruption or mesenteric segment aneurysm recurrence requiring redo Extent IV reconstruction).

DTA repair with one of the following: Safi extent C coverage. Subclavian to diaphragm disease extent. >75% of total DTA length.

-TEVAR with one of the following: Full DTA coverage with previous abdominal EVAR or open AAA. Full DTA coverage including Zone 2 to celiac (i.e., distal arch plus full coverage DTA).

Full DTA coverage with celiac artery coverage with or without left subclavian artery coverage (Zone 2 or Zone 3 proximal landing), or full DTA (either Zone 2 or Zone 3) with extension distal to celiac with visceral debranching (e.g., the abdominal hybrid Extent 2 TAAA).

Note: Zone 2 is defined as between the left carotid through coverage of the left subclavian artery and Zone 3 is defined as the first 3cm distal to the left subclavian (e.g., between left subclavian and ligamentum [isthmus]).

Completed any staging or bypass procedure that precedes the aortic repair at least 48 hours prior to the repair.

Expect placement of a lumbar CSF catheter during the procedure with plans to maintain it for at least 48 hours per the treating physician.

Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.

A female subject is eligible to participate if she is of:

Non-childbearing potential defined as pre-menopausal females with a documented tubal ligation or hysterectomy; or postmenopausal defined as 12 months of spontaneous amenorrhea [in questionable cases a blood sample with simultaneous follicle stimulating hormone (FSH) > 40 milli international unit /mililiter (mL) and estradiol < 40 picogram/mL (<147 picomoles/Liter) is confirmatory]. Females on hormone replacement therapy (HRT) and whose menopausal status is in doubt will be required to use one of the contraception methods if they wish to continue their HRT during the study. Otherwise, they must discontinue HRT to allow confirmation of post-menopausal status prior to study enrollment. For most forms of HRT, at least 2-4 weeks will elapse between the cessation of therapy and the blood draw; this interval depends on the type and dosage of HRT. Following confirmation of their post-menopausal status, they can resume use of HRT during the study without use of a contraceptive method.

Child-bearing potential and agrees to use one of the contraception methods from screening until completion of the Follow-up Visit.

Male subjects with female partners of child-bearing potential must agree to use one of the contraception methods. This criterion must be followed from the time of Screening until the completion of the Follow-up Visit.

Exclusion Criteria

The subject has a traumatic aortic dissection.

The subject has a baseline NIHSS > 1 or modified Rankin Scale > 1.

The subject has a history of myocardial infarction, stroke, or spinal infarct within the past 3 months.

The subject has active ulcer disease or recent gastrointestinal bleeding within the past 6 months.

The subject has a history of deep venous thrombosis or pulmonary embolism in the past 12 months.

The subject has been treated for a malignancy (excluding non-melanomatous skin cancers) within the past 12 months and is not confirmed to be disease free.

The subject has had treatment for retinal neovascularization (e.g., diabetic proliferative retinopathy or age related macular degeneration) within 3 months of randomization.

The subject is currently receiving dialysis.

The subject is currently receiving or expected to require treatment (within the study period) with erythropoiesis medication such as epoetin alfa (Procrit, Epogen), or darbepoetin alfa (Aranesp).

History of regular alcohol consumption within 6 months of the study defined as: an average weekly intake of >14 drinks for males or >7 drinks for females. One drink is equivalent to 12 g of alcohol: 12 ounces (360 mL) of beer, 5 ounces (150 mL) of wine or 1.5 ounces (45 mL) of 80 proof distilled spirits.

The subject has participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer).